During drilling of an oil well or another effluent (in particular gas, vapor, water), it is known to analyze the drilling fluid emerging from the well in order to obtain useful information on the well being drilled.
To that end, by analyzing, for example, the gaseous compounds and the drilling debris contained in the drilling mud emerging from the well, it is possible to reconstitute the geological succession of the formations passed through during the drilling, which plays a role in determining exploitation possibilities of the fluid deposits encountered.
Moreover, a certain number of other analyses are done on the drilling fluid emerging from the well or possibly injected into the well. To that end, it is known to recover, at regular intervals, samples of drilling fluid and to analyze those samples in a laboratory present on the drilling site. These analyses comprise in particular the determination of the rheological properties of the drilling fluid to determine its viscosity. The drilling fluid is in fact generally a non-newtonian fluid, or even a thixotropic fluid.
This analysis is intended in particular to assess the behavior of the fluid during different drilling phases.
In particular, when the drilling is stopped for a fairly long period of time, the drilling fluid present in the well can have a notable increase in viscosity, which must be taken into account when the pumps ensuring circulation of the drilling fluid in the well are restarted.
The measurement of the rheological properties of a fluid is generally done according to the standards recommended by the American Petroleum Institute (API). To that end, a drilling fluid sample is taken at regular intervals by the operator, for example at a mud pit. The recovered sample is then conveyed by the operator to the measuring booth where it is placed in a measuring assembly of the aforementioned type, as described in U.S. Pat. No. 4,484,468, for example.
Such a measuring assembly generally includes a rotary hollow container, able to be driven in rotation at chosen speeds of rotation. It also includes a pin arranged in the hollow container and delimiting, with the container, an intermediate space receiving the fluid to be measured.
The pin is mounted partially free in rotation around its axis. During the measurement, the container is driven in rotation around its axis at a given speed of rotation, which partially drives the drilling fluid in rotation under the effect of the shearing. Information representative of the force applied by the drilling fluid on the pin during the rotation of the container is collected by a sensor. The sensor for example measures the degree of rotation of the insert around its axis for different speeds of rotation of the container.
Such a device is not completely satisfactory. It in fact requires significant labor and continuous interventions on the well, in particular in the secured zone around the well. In fact, this measurement is typically only done 4 to 6 times per day, which does not make it possible to identify all of the rheological changes.
Moreover, the precision of the measurement depends on the quality of the sample taken by the operator, and also the quality of the measurement done by the operator.
One aim of the disclosure is therefore to obtain an assembly for measuring the rheological properties of a drilling fluid, that is simple and reliable to use, in particular on a drilling site, and that nevertheless makes it possible to obtain precise and reproducible measurements, in particular according to the existing standards.